Oral administration in horses refers to the delivery of medications, supplements, or nutrients via the mouth. This method is commonly used in equine veterinary medicine for its practicality and ease of use. Oral formulations can include powders, pastes, or liquids, which are designed to be palatable and easily ingested by horses. The effectiveness of oral administration depends on factors such as the horse's digestive physiology, the formulation of the product, and the consistency with which it is administered. This page compiles peer-reviewed research studies and scholarly articles that explore the techniques, efficacy, and considerations of oral administration in equine care.
Pusterla N, Hilton H, Wattanaphansak S, Collier JR, Mapes SM, Stenbom RM, Gebhart C.Equine proliferative enteropathy (EPE) caused by Lawsonia intracellularis has recently been recognized as an emerging disease in foals. Whilst the clinical entity, diagnostic evaluation and treatment of affected foals have been well established and described, preventive measures for EPE have remained largely unaddressed. The objectives of this study were to investigate the humoral immune response and onset and duration of fecal shedding in foals after oral and intra-rectal administration of a modified-live vaccine of L. intracellularis. Foals were vaccinated twice, 3 weeks apart, via oral dren...
Garré B, Gryspeerdt A, Croubels S, De Backer P, Nauwynck H.The purpose of the current study was to investigate the therapeutic efficacy of valacyclovir against EHV1 in a controlled study. Eight naïve Shetland ponies were inoculated with 10(6.5) TCID(50) of the neuropathogenic strain 03P37. Four ponies were treated with valacyclovir at a dosage of 40mg/kg bodyweight, 3 times daily, for 5 (n=2) or 7 (n=2) consecutive days, while the other four ponies served as untreated controls. The treatment regimen started 1h before inoculation. Ponies were monitored daily for clinical signs. At 0, 1, 2, 3, 4, 5, 7, 9, 11, 14, 17 and 21 days post inoculation (d pi),...
Meulyzer M, Vachon P, Beaudry F, Vinardell T, Richard H, Beauchamp G, Laverty S.To compare synovial glucosamine levels in normal and inflamed equine joints following oral glucosamine administration and to determine whether single dose administration alters standard synovial parameters of inflammation. Methods: Eight adult horses were studied. On weeks 1 and 2, all horses received 20mg/kg glucosamine hydrochloride by nasogastric (NG) intubation or intravenous injection. On weeks 3 and 4, 12h after injection of both radiocarpal joints with 0.25 ng Escherichia coli lipopolysaccharide (LPS) to induce inflammation, glucosamine hydrochloride or a placebo was administered by NG ...
Maxwell LK, Bentz BG, Bourne DW, Erkert RS.Recent outbreaks of equine herpes virus type-1 infections have stimulated renewed interest in the use of effective antiherpetic drugs in horses. The purpose of this study was to investigate the pharmacokinetics of valacyclovir (VCV), the prodrug of acyclovir (ACV), in horses. Six adult horses were used in a randomized cross-over design. Treatments consisted of 10 mg/kg ACV infused intravenously, 5 g (7.7-11.7 mg/kg) VCV delivered intragastrically (IG) and 15 g (22.7-34.1 mg/kg) VCV administered IG. Serum samples were obtained at predetermined times for acyclovir assay using high-performance li...
Okamura K, Sasaki N, Fukunaka M, Yamada H, Inokuma H.The prokinetic effect of the 5-HT4 receptor agonist mosapride was evaluated in seven healthy thoroughbreds. Mosapride was orally administered at doses of 0.5, 1.0 or 1.5 mg/kg. The breath 13CO2/12CO2 rate (Delta13CO2), an indirect indicator for the rate of gastric emptying, was measured at appropriate points for 4 hr after drug administration. There was a significant increase compared with the control value at 15, 20 and 165 min for 0.5 mg/kg, 30 min at 1.0 mg/kg and 165 min for 1.5 mg/kg. The results suggest that mosapride may facilitate the gastric emptying in horses.
Longhofer SL, Reinemeyer CR, Radecki SV.The efficacy of top-dress antiinflammatory drugs ultimately depends on a patient's willingness to consume treated feed. The current study compares the palatability of two phenylbutazone top-dress formulations (Equipalazone Powder, Dechra Pharmaceuticals, and Pro-Dynam, VetXX, Ltd.) and a suxibuzone top-dress formulation (Danilon Equidos, Janssen Animal Health). Results of a three-period, crossover study on 18 healthy horses showed that Pro-Dynam was significantly less palatable, with significantly less consumption of treated feed compared with either Equipalazone Powder or Danilon Equidos. The...
Higgins JK, Puschner B, Kass PH, Pusterla N.To determine concentrations of alpha-tocopherol in serum and CSF of healthy horses following administration of supplemental vitamin E in feed. Methods: 10 healthy adult horses. Methods: Horses were allocated to receive supplemental d-alpha-tocopherol (1,000 U/d [group A; n=5] or 10,000 U/d [group B; 5]) in feed for 10 days. Blood samples were collected before (baseline), during, and at intervals for 10 days after discontinuation of vitamin E administration for assessment of serum alpha-tocopherol concentration. Cerebrospinal fluid samples were collected prior to and 24 hours after cessation of...
Raidal SL, Edwards S.To determine the pharmacokinetics of potassium bromide (KBr) in horses after a single and multiple oral doses. Methods: Twelve adult Standardbred and Thoroughbred mares. Methods: Horses were randomly assigned into two treatment groups. In Part 1 of the study, horses were given a single oral dose of 120 mg/kg KBr. Part 2 of the study evaluated a loading dose of 120 mg/kg KBr daily by stomach tube for 5 days, followed by 40 mg/kg daily in feed for 7 days. Serum concentrations of bromide were determined by colorimetric spectrophotometry following drug administration to permit determination of con...
Soma LR, Rudy JA, Uboh CE, Xu F, Snapp HM.To investigate the pharmacokinetics and behavioral effects of aminorex administered IV and PO in horses. Methods: 7 Thoroughbreds. Methods: In a cross-over design, aminorex (0.03 mg/kg) was administered IV or PO. Plasma and urinary aminorex concentrations were determined via liquid chromatography- mass spectrometry. Results: Decrease of aminorex from plasma following IV administration was described by a 3-compartment pharmacokinetic model. Median (range) values of alpha, beta, and gamma half-lives were 0.04 (0.01 to 0.28), 2.30 (1.23 to 3.09), and 18.82 (8.13 to 46.64) hours, respectively. Tot...
Hallowell GD.Cases with a history of colic due to a large colonic impaction were recruited retrospectively to assess the treatment efficacy and complications of oral and parenteral fluid therapy regimes for correction of primary large colon impactions. Oral isotonic fluids had been administered at varying intervals following initial treatment with magnesium sulphate and water. There was no significant difference in complication rates between groups. Considering complication rates with impaction clearance, hourly administration of oral fluids appears to be the most appropriate treatment regime of those inve...
Meulyzer M, Vachon P, Beaudry F, Vinardell T, Richard H, Beauchamp G, Laverty S.To compare the pharmacokinetics of glucosamine and the synovial fluid levels attained following treatment with glucosamine sulphate or glucosamine hydrochloride in a large animal model at clinically relevant doses. Methods: Eight adult female horses were used. Crystalline glucosamine sulphate (Dona) or glucosamine hydrochloride was administered at a dose of 20 mg/kg by either intravenous (i.v.) injection or nasogastric (n.g.) intubation. Plasma samples were collected before dosing and at 5, 15, 30, 60, 120, 360, 480 and 720 min after dosing. Synovial fluid samples were collected from the radio...
Mackay RJ, Tanhauser ST, Gillis KD, Mayhew IG, Kennedy TJ.To evaluate the effect of intermittent oral administration of ponazuril on immunoconversion against Sarcocystis neurona in horses inoculated intragastrically with S neurona sporocysts. Methods: 20 healthy horses that were seronegative for S neurona-specific IgG. Methods: 5 control horses were neither inoculated with sporocysts nor treated. Other horses (5 horses/group) each received 612,500 S neurona sporocysts via nasogastric tube (day 0) and were not treated or were administered ponazuril (20 mg/kg, PO) every 7 days (beginning on day 5) or every 14 days (beginning on day 12) for 12 weeks. Bl...
Keegan KG, Messer NT, Reed SK, Wilson DA, Kramer J.To determine the effectiveness of administering multiple doses of phenylbutazone alone or a combination of phenylbutazone and flunixin meglumine to alleviate lameness in horses. Methods: 29 adult horses with naturally occurring forelimb and hind limb lameness. Methods: Lameness evaluations were performed by use of kinematic evaluation while horses were trotting on a treadmill. Lameness evaluations were performed before and 12 hours after administration of 2 nonsteroidal anti-inflammatory drug (NSAID) treatment regimens. Phenylbutazone paste was administered at approximately 2.2 mg/kg, PO, ever...
Clark C, Dowling PM, Ross S, Woodbury M, Boison JO.The macrolide antibiotic tilmicosin has potential for treating bacterial respiratory tract infections in horses. A pharmacokinetic study evaluated the disposition of tilmicosin in the horse after oral (4 mg/kg) or subcutaneous (s.c.) (10 mg/kg) administration. Tilmicosin was not detected in equine plasma or tissues after oral administration at this dose. With s.c. injection, tilmicosin concentrations reached a maximum concentration of approximately 200 ng/mL in the plasma of the horses. Tilmicosin concentrations in plasma persisted with a mean residence time (MRT) of 19 h. Maximum tissue resid...
Shilo Y, Britzi M, Eytan B, Lifschitz T, Soback S, Steinman A.Tramadol is a centrally acting analgesic drug that has been used clinically for the last two decades to treat moderate to moderately severe pain in humans. The present study investigated tramadol administration in horses by intravenous, intramuscular, oral as immediate-release and oral as sustained-release dosage-form routes. Seven horses were used in a four-way crossover study design in which racemic tramadol was administered at 2 mg/kg by each route of administration. Altogether, 23 blood samples were collected between 0 and 2880 min. The concentration of tramadol and its M1 metabolite were ...
Frank N, Buchanan BR, Elliott SB.To determine the effects of long-term oral levothyroxine sodium (L-T(4)) administration on serum thyroid hormone concentrations, thyroid gland function, clinicopathologic variables, and echocardiographic examination measurements in adult euthyroid horses. Methods: 6 healthy adult mares. Methods: Horses received L-T(4) (48 mg/d) orally for 48 weeks. Every 4 weeks, physical examinations were performed; blood samples were collected for CBC, plasma biochemical analyses, and assessments of serum total triiodothyronine (tT(3)) and thyroxine (tT(4)) concentrations. Plasma creatine kinase MB activity ...
Doucet MY, Bertone AL, Hendrickson D, Hughes F, Macallister C, McClure S, Reinemeyer C, Rossier Y, Sifferman R, Vrins AA, White G, Kunkle B, Alva R....To compare efficacy and safety of paste formulations of firocoxib and phenylbutazone in horses with naturally occurring osteoarthritis. Methods: Randomized controlled clinical trial. Methods: 253 client-owned horses with naturally occurring osteoarthritis. Methods: Horses were treated with firocoxib (0.1 mg/kg [0.045 mg/lb], PO, q 24 h) or phenylbutazone (4.4 mg/kg [2 mg/lb], PO, q 24 h) for 14 days. Physical examinations and lameness evaluations were performed prior to treatment and after 7 and 14 days. Clinical improvement was defined as a reduction of at least 1 lameness grade or a combined...
Frank N, Elliott SB, Boston RC.To determine the effects of long-term oral administration of levothyroxine sodium (L-T(4)) on glucose dynamics in adult euthyroid horses. Methods: 6 healthy adult mares. Methods: Horses received L-T(4) (48 mg/d) orally for 48 weeks. Frequently sampled IV glucose tolerance test procedures were performed on 3 occasions (24-hour intervals) before and at 16, 32, and 48 weeks during the treatment period. Data were assessed via minimal model analysis. The repeatability of measurements was evaluated. Results: During treatment, body weight decreased significantly from the pretreatment value; mean +/- ...
Waller A, Lindinger MI.Sodium acetate (NaAcetate) has received some attention as an alkalinizing agent and possible alternative energy source for the horse, however the effects of oral administration remain largely unknown. The present study used the physicochemical approach to characterize the changes in acid-base status occurring after oral NaAcetate/acetic acid (NAA) administration in horses. Methods: Jugular venous blood was sampled from 9 exercise-conditioned horses on 2 separate occasions, at rest and for 24 h following a competition exercise test (CET) designed to simulate the speed and endurance test of 3-da...
Javsicas LH, Sanchez LC.Administration of omeprazole paste per os to healthy neonatal foals has been shown to effectively increase intragastric pH, but has not been evaluated in sick neonatal foals. Objective: To determine the effect of orally administered omeprazole paste on intragastric pH in clinically ill neonatal foals requiring nasogastric intubation. Methods: Intragastric pH was measured continuously for 24 h using an indwelling electrode and continuous data recording system in hospitalised neonatal foals age < or =2 days. Intragastric pH was measured for 12 h prior to (pretreatment period) and 12 h followi...
Colitz CM, Latimer FG, Cheng H, Chan KK, Reed SM, Pennick GJ.To determine the pharmacokinetics of voriconazole following IV and PO administration and assess the distribution of voriconazole into body fluids following repeated PO administration in horses. Methods: 6 clinically normal adult horses. Methods: All horses received voriconazole (10 mg/kg) IV and PO (2-week interval between treatments). Plasma voriconazole concentrations were determined prior to and at intervals following administration. Subsequently, voriconazole was administered PO (3 mg/kg) twice daily for 10 days to all horses; plasma, synovial fluid, CSF, urine, and preocular tear film con...
Fuller MC, Abutarbush SM.A 10-year-old gelding was presented with a tongue that had swelled immediately after oral administration of oxfendazole, using an udder infusion cannula. The tongue appeared to have been punctured inadvertently. The horse recovered after treatment with intravenous fluid, antibiotics, and anti-inflammatory drugs. Administering oral medication by this method should be discouraged. Un cheval hongre âgé de 10 ans a été présenté avec une langue devenue tuméfiée immédiatement après l’administration orale d’oxfendazole à l’aide d’une canule à infusion du pis. La langue semblait a...
Garré B, Shebany K, Gryspeerdt A, Baert K, van der Meulen K, Nauwynck H, Deprez P, De Backer P, Croubels S.The purpose of this study was twofold. The first aim was to evaluate the oral bioavailability and pharmacokinetics (PKs) of acyclovir in horses after intravenous (i.v.) administration and after oral administration of acyclovir and its prodrug, valacyclovir. Second, we aimed to combine these PK data with pharmacodynamic (PD) information, i.e., 50% effective concentrations (EC(50) values) from in vitro studies, to design an optimal dosage schedule. Three treatments were administered to healthy adult horses: 10 mg of acyclovir/kg of body weight delivered as an i.v. infusion over 1 h, 20 mg of acy...
Olsén L, Bondesson U, Broström H, Tjälve H, Ingvast-Larsson C.The pharmacokinetics of the histamine H(1)-antagonist cetirizine and its effect on histamine-induced cutaneous wheal formation were studied in six healthy horses following repeated oral administration. After three consecutive administrations of cetirizine (0.2 mg/kg body weight, bw) every 12h, the trough plasma concentration of cetirizine was 16+/-4 ng/mL (mean+/-SD) and the wheal formation was inhibited by 45+/-23%. After four additional administrations of cetirizine (0.4 mg/kg bw) every 12 h, the trough plasma concentration was 48+/-15 ng/mL and the wheal formation was inhibited by 68+/-11%....
Camargo FC, Robinson NE, Berney C, Eberhart S, Baker S, Detolve P, Derksen FJ, Lehner AF, Hughes C, Tobin T.The bronchodilator effects of trimetoquinol (TMQ) have been studied when administered i.v. or intratracheally, but not in an aerosolised form. Objective: To define the relationship between the therapeutic and adverse responses (therapeutic index) of TMQ when administered as an aerosol or by the oral route. Methods: Increasing doses of TMQ were administered to horses with heaves as an aerosol and by the oral route. Dose ranged 100-1000 microg/horse for aerosolised TMQ and from 6-60 microg/kg bwt for the oral route. Airway and cardiac effects were assessed by measurement of maximal change in ple...
Womble A, Giguère S, Lee EA.The objective of this study was to determine the disposition of orally administered doxycycline in foals. Six healthy 4- to 8-week-old foals were used. Doxycycline was administered to each foal via the intragastric (IG) route at dosages of 10 and 20 mg/kg, in a cross-over design. After the first 10 mg/kg dose, five additional doses were administered at 12-h intervals. A microbiological assay was used to measure doxycycline activity in serum, urine, peritoneal fluid, synovial fluid, cerebrospinal (CSF), pulmonary epithelial lining fluid (PELF), and bronchoalveolar (BAL) cells. Following adminis...
Kvaternick V, Pollmeier M, Fischer J, Hanson PD.The primary objective of this study was to determine the pharmacokinetic profile of firocoxib, a novel second generation coxib, in horses. Horses were administered either a single oral or intravenous dose of firocoxib at 0.1 mg/kg in a two-period crossover study with 12 animals. The dosage was based on previously determined pharmacodynamic parameters. Oral firocoxib was well absorbed with an average bioavailability (absolute) of 79% and a Cmax of 75 ng/mL at 3.9 h. The average elimination half-life was 30 h. Following intravenous administration the average Cmax was 210 ng/mL and the eliminatio...
Olsén L, Ingvast-Larsson C, Bondesson U, Broström H, Tjälve H, Larsson P.The pharmacokinetics of the histamine H(1)-antagonist cetirizine and the effects of pretreatment with the antiparasitic macrocyclic lactone ivermectin on the pharmacokinetics of cetirizine were studied in horses. After oral administration of cetirizine at 0.2 mg/kg bw, the mean terminal half-life was 3.4 h (range 2.9-3.7 h) and the maximal plasma concentration 132 ng/mL (101-196 ng/mL). The time to reach maximal plasma concentration was 0.7 h (0.5-0.8 h). Ivermectin (0.2 mg/kg bw) given orally 1.5 h before cetirizine did not affect its pharmacokinetics. However, ivermectin pretreatment 12 h be...
Ross DH, Heird C, Byrd JW, Beauchemin V, Kiess W.The safety of a feed-thru pellet formulation containing the insect growth regulator diflubenzuron (0.24%) for control of manure-breeding flies (Musca domestica L. and Stomoxys calcitrans L.) in horses was evaluated. Pellets were administered orally at 0, 1, 3, and 5 times the clinical dosage (0.12 to 0.20 mg/kg) on a daily basis for 31 consecutive days. Variables examined included daily clinical observations, hematology, coagulation, serum chemistry, acetylcholinesterase inhibition, body weights, and physical examinations. Horses remained healthy throughout the study, and no adverse reactions ...
Yamanaka T, Yamada M, Tsujimura K, Kondo T, Nagata S, Hobo S, Kurosawa M, Matsumura T.The aim of this study was to investigate the pharmacokinetics of oseltamivir carboxylate (OC) in horses (n=6) after oral administration of its prodrug oseltamivir. The binding rate of OC to horse plasma proteins was negligible (<1%). Oral administration of oseltamivir of 2 mg/kg body weight of oseltamivir to horses provided a plasma concentration of OC (mean maximum concentration: 257.9 ng/ml) above the inhibitory concentrations against equine influenza A viruses determined in vitro. However, because OC is rapidly eliminated from horse plasma (mean elimination half-life: 2.5 hr), administratio...
Marsh MV, Caldwell J, Sloan TP, Smith RL, Horner M, Moss MS.14C-Fenclofenac (2-(2'-4'-dichlorophenoxy)-phenylacetic acid) was administered orally to horses, and urinary metabolites investigated by chromatography. Fenclofenac was rapidly absorbed and eliminated, with a plasma half-life (t1/2) of 2.3 h, with 83.2 and 85.8% of the dose being recovered in the urine in 0-24 h. The major urinary metabolite was the ester glucuronide (58.8, 70.0% dose), and evidence is presented that this metabolite undergoes a structural rearrangement to give beta-glucuronidase-resistant isomers. The other 14C-labelled components in horse urine were unchanged fenclofenac (13....
Waller A, Lindinger MI.Sodium acetate (NaAcetate) has received some attention as an alkalinizing agent and possible alternative energy source for the horse, however the effects of oral administration remain largely unknown. The present study used the physicochemical approach to characterize the changes in acid-base status occurring after oral NaAcetate/acetic acid (NAA) administration in horses. Methods: Jugular venous blood was sampled from 9 exercise-conditioned horses on 2 separate occasions, at rest and for 24 h following a competition exercise test (CET) designed to simulate the speed and endurance test of 3-da...
Wang J, Qiu J, Xiao H, Gong X, Sun P, Li J, Zhang S, Cao X.The pharmacokinetic properties of three formulations of vitacoxib were investigated in horses. To describe plasma concentrations and characterize the pharmacokinetics, 6 healthy adult Chinese Mongolian horses were administered a single dose of 0.1 mg/kg bodyweight intravenous (i.v.), oral paste, or oral tablet vitacoxib in a 3-way, randomized, parallel design. Blood samples were collected prior to and at various times up to 72 hr postadministration. Plasma vitacoxib concentrations were quantified using UPLC-MS/MS, and pharmacokinetic parameters were calculated using noncompartmental analysis...
Pérez R, Godoy C, Palma C, Muñoz L, Arboix M, Alvinerie M.A study was done to compare plasma disposition kinetics and the fecal elimination profile of doramectin (DRM) after oral or intramuscular (IM) administration in horses. Ten clinically healthy horses, 328-502 kg body weight (bw), were assigned to 2 experimental groups of 5 horses each. Group 1 was treated with an oral dose of 0.2 mg DRM/kg bw, while Group 2 was treated with 0.2 mg DRM/kg bw by IM route. Blood and fecal samples were collected at different times between 0.5h and 60 days post-treatment. After plasma and fecal drug extraction and derivatization, samples were analysed by high perfor...
Davis JL, Gardner SY, Jones SL, Schwabenton BA, Papich MG.The properties of azithromycin suggest that it may be an alternative to erythromycin for treatment of Rhodococcus equi pneumonia in foals. To investigate this possibility, the disposition of azithromycin in plasma, polymorphonuclear leukocytes (PMN), and alveolar cells was examined after a single administration in foals. Azithromycin suspension was administered orally (p.o.) at a dose of 10 mg/kg to five healthy 2-3-month-old foals. Two weeks later, azithromycin for injection was administered by intravenous (i.v.) infusion at a dose of 5 mg/kg to the same foals. Plasma samples were collected a...
Breuhaus BA, DeGraves FJ, Honore EK, Papich MG.To determine pharmacokinetics of ibuprofen in healthy foals and to determine clinical effects after oral administration for 6 days. Methods: 7 healthy 5- to 10-week-old foals. Methods: Serum concentrations of ibuprofen were measured after IV and oral (nasogastric tube) administration at dosages of 10 and 25 mg/kg of body weight. Foals were given ibuprofen (25 mg/kg, PO, q 8 h) as a paste for 6 days. Serum and urine were obtained before and after the 6-day period. Results: Half-life of elimination (Kel t1/2) of IV-administered ibuprofen (ie, 10 and 25 mg/kg), was 79 and 108 minutes, maximal ser...
Haven ML, Dave K, Burrow JA, Merritt AM, Harris D, Zhang D, Hickey GJ.The antisecretory activity of omeprazole on gastric acid when administered i.v., intragastrically or per os, was evaluated in 2 female and 3 castrated male horses. Each horse had been prepared with a chronic indwelling gastric cannula. A single i.v. administration of omeprazole (1.5 mg/kg bwt) was effective in abolishing basal and pentagastrin (PG)-stimulated acid secretion. Once daily, nasogastric administration of omeprazole in acid-stable granules for 5 days inhibited acid secretion in a dose-dependent manner: 57% (1.5 mg/kg bwt) and 98% (5.0 mg/kg bwt) reduction of PG-stimulated acid secre...
Estell KE, Knych HK, Patel T, Edman JM, Magdesian KG.To the authors' knowledge, there have been no studies evaluating the pharmacokinetics of chloramphenicol administered orally to horses at the currently recommended dose of 50 mg/kg PO q6 h for multiple days. The published antimicrobial susceptibility breakpoint is 8.0 ug/mL; it is unknown if this concentration is achievable at the recommended dose rate in horses. The aim of this prospective multi-dose pharmacokinetic study was to perform pharmacokinetic analysis of chloramphenicol after multiple doses. The authors hypothesize that the antimicrobial susceptibility breakpoint will not be reached...
Ralston S, Stives M.Though horses synthesize ascorbic acid in their liver in amounts that meet their needs under normal circumstances, prolonged stress results in low plasma concentrations due to enhanced utilization and renal excretion and can reduce immune function. It was hypothesized that plasma ascorbic acid could be maintained in weanling horses by oral supplementation following prolonged transportation. Weanlings were supplemented with no ascorbic acid (Tx 0: n = 4), 5 grams ascorbic acid twice daily for 5 days (Tx 1: n = 4) or for 10 days (Tx 2: n = 4) following >50 hours of transportation. Supplementa...
Mogg TD, Pollitt CC, Willmore JP, Thompson H.Three groups of horses and ponies (N = 13, 13 and 12) were treated with ivermectin paste (0.2 mg/kg p.o.), avermectin B1 solution (0.2 mg/kg p.o.), or fenbendazole suspension (10 mg/kg via nasogastric tube). The avermectin B1 was a 1% solution in a propylene glycolglycerol formal base. Faecal strongyle egg counts were performed before, and 14, 28, 42, 56 and 70 d, after treatment. Full-thickness skin biopsies from the neck, pectoral and umbilical regions were examined for Onchocera microfilaria before treatment, and again 14 and 70 d later. Ivermectin therapy produced a significant (P less tha...
Littlewood JD, Rose JF, Paterson S.A single blind controlled clinical trial of oral ivermectin paste at a dose rate of 0.1 mg/kg daily for seven days for the treatment of chorioptic mange in horses was carried out. There was a statistically significant reduction in the numbers of mites in the samples taken from the treated horses compared with the untreated horses, but the mites were not eliminated from all the treated animals. Two further groups of horses were treated, one at a dose rate of 0.1 mg/kg daily for 10 days and the other with two doses of 0.2 mg/kg given two weeks apart. There were no statistically significant diffe...
Easton-Jones CA, Madigan JE, Barnum S, Maxwell LK, Taylor SD, Arnesen T, Pusterla N.Equine herpesvirus-5 is commonly isolated from the lungs of horses with EMPF, suggesting an etiological link. Valacyclovir is used empirically to treat EMPF; however, no data is available concerning its impact on EHV-5 viral kinetics. Objective: To determine the effect of oral administration of valacyclovir on EHV-5 viral load measured by qPCR in blood, nasal secretions (NS) and BALF in horses with EMPF. Methods: Six horses diagnosed with EMPF. Methods: A prospective clinical trial was performed. Horses received 10 days of PO administered valacyclovir (loading dose 30 mg/kg, maintenance dose 2...
Higgins AJ, Lees P, Sedgwick AD, Buick AR, Churchus R.In a two-part cross-over experiment in six ponies, an acute inflammatory reaction was generated by injecting carrageenin solution into subcutaneously-implanted tissue-cages lined with fibrovascular granulation tissue. In each part of the cross-over, half of the ponies received a novel phenylpyrazoline anti-inflammatory agent (BW540C) orally and half received a placebo treatment. BW540C inhibited platelet cyclo-oxygenase for 24 h but the reductions in exudate eicosanoid concentrations were less pronounced. A significant suppression in the rise of surface skin temperature in BW540C-treated ponie...
Dirikolu L, Karpiesiuk W, Lehner AF, Hughes C, Granstrom DE, Tobin T.Triazine-based antiprotozoal agents are known for their lipophylic characteristics and may therefore be expected to be well absorbed following oral administration. However, although an increase in lipid solubility generally increases the absorption of chemicals, extremely lipid-soluble chemicals may dissolve poorly in gastrointestinal (GI) fluids, and their corresponding absorption and bioavailability would be low. Also, if the compound is administered in solid form and is relatively insoluble in GI fluids, it is likely to have limited contact with the GI mucosa, and therefore, its rate of abs...
Noble GK, Li X, Zhang D, Sillence MN.Tryptophan (TRP) is marketed as a calmative for horses despite reservations about its efficacy. The aim of this study was to measure the effect of oral TRP administration on the reaction speed of horses. Sixty mature horses were used in a two stage randomised, blind, cross-over study, receiving a placebo and an oral dose of TRP (30, 60 or 120 mg/kg body weight), before undergoing a reaction speed test. Blood samples were taken up to 96 h after TRP administration, to identify signs of acute haemolytic anaemia. Plasma TRP concentrations were increased (P <0.001) by the administration of...
Javsicas LH, Sanchez LC.Administration of omeprazole paste per os to healthy neonatal foals has been shown to effectively increase intragastric pH, but has not been evaluated in sick neonatal foals. Objective: To determine the effect of orally administered omeprazole paste on intragastric pH in clinically ill neonatal foals requiring nasogastric intubation. Methods: Intragastric pH was measured continuously for 24 h using an indwelling electrode and continuous data recording system in hospitalised neonatal foals age < or =2 days. Intragastric pH was measured for 12 h prior to (pretreatment period) and 12 h followi...
Love DN, Rose RJ, Martin IC, Bailey M.Amoxycillin trihydrate was administered orally to 6 foals at dose rates of 13 mg/kg (low), 20 mg/kg (medium) and 30 mg/kg (high) and serum concentrations determined at intervals up to 8 h. Therapeutic serum levels of 1 microgram/ml persisted for 268 mins at a dose rate of 13 mg/kg, for 339 mins at 20 mg/kg and for 381 mins at 30 mg/kg. A 2 micrograms/ml serum level persisted for 198 mins at a dose rate of 13 mg/kg, for 268 mins at 20 mg/kg and for 311 mins at 30 mg/kg. To determine the spectra of its antibacterial activity, the minimum inhibitory concentrations of amoxycillin against 8 genera ...
Hartnack AK, Van Metre DC, Morley PS.To evaluate the potential association between Salmonella enterica shedding in hospitalized horses and the risk of diarrhea among stablemates, and to characterize gastrointestinal-related illness and death following discharge among horses that shed S. enterica while hospitalized. Methods: Retrospective cohort study [corrected]. Methods: 221 horses (59 that shed S. enterica during hospitalization and 162 that tested negative for S. enterica shedding ≥ 3 times during hospitalization). Methods: Information from medical records (signalment, results of microbial culture of fecal samples, clinical ...
Törneke MK, Ingvast-Larsson JC, Johansson JM, Appelgren LE.To determine pharmacokinetics of terbutaline in healthy horses and to relate serum terbutaline concentrations with the drug's pharmacodynamic effects. Methods: 6 healthy horses. Methods: Horses were given terbutaline i.v. (10 microg/kg of body weight) and, 1 week later, p.o. (100 microg/kg). Responses to drug administration (eg, heart rate and serum lactate concentration) were measured. Serum terbutaline concentration was measured by means of gas chromatography with mass spectrometry. Protein binding was determined in vitro. Results: Following i.v. administration, median maximum serum terbutal...
Swor TM, Whittenburg JL, Chaffin MK.3 adult Quarter Horses were evaluated for acute, progressive neurologic signs 18 hours after oral administration of 1 dose of 1.87% ivermectin paste. Results: Clinical signs included depression, forelimb and hind limb ataxia, drooping of the superior and inferior lips, and muscle fasciculations. Bilateral mydriasis, decreased pupillary light reflexes, and absent menace reflexes were evident. Clinical signs progressed in severity for 36 hours after administration of the ivermectin. Results: All horses were treated supportively with IV administration of fluids and anti-inflammatory medications. ...
Garré B, Baert K, Nauwynck H, Deprez P, De Backer P, Croubels S.The aim of the current study was to investigate whether multiple oral dosing of valacyclovir could result in plasma concentrations exceeding the EC(50)-value of acyclovir against equine herpesvirus 1 (EHV1) during the majority of the treatment period. Additionally, we wanted to determine the concentration of acyclovir in nasal mucus and cerebrospinal fluid (CSF). Valacyclovir was administered to four horses and two ponies, three times daily, at a dosage of 40 mg/kg, for four consecutive days. Blood was collected prior to each administration and 1 h after dosing. Nasal mucus samples and CSF wer...
Cox S, Villarino N, Doherty T.The determination of the pharmacokinetic parameters of tramadol in plasma and a better characterization of its metabolites after oral administration to horses is necessary to design dosage regimens to achieve target plasma concentrations that are associated with analgesia. The purpose of this study was to determine the pharmacokinetics and elimination pattern in urine of tramadol and its metabolites after oral administration to horses. Tramadol was administered orally to six horses and its half-life, T(max) and C(max) in plasma were 10.1, 0.59 h, and 132.7 ng/mL, respectively. The half-life, T...
Prades M, Brown MP, Gronwall R, Houston AE.After single oral administration of ketoconazole (30 mg/kg bodyweight [bwt]) in 50 ml of corn syrup to a healthy mare, the drug was not detected in serum. Ketoconazole in 0.2 N HC1 was administered intragastrically to six healthy adult horses in five consecutive doses of 30 mg/kg bwt at 12 h intervals. Ketoconazole concentrations were measured in serum, synovial fluid, peritoneal fluid, cerebrospinal fluid (CSF), urine and endometrium. Mean peak serum ketoconazole concentration was 3.76 micrograms/ml at 1.5 to 2 h after intragastric administration. Mean peak synovial concentration was 0.87 mic...
Knych HK, Corado CR, McKemie DS, Scholtz E, Sams R.Tramadol is a synthetic opioid used in human medicine, and to a lesser extent in veterinary medicine, for the treatment of both acute and chronic pain. In humans, the analgesic effects are owing to the actions of both the parent compound and an active metabolite (M1). The goal of the current study was to extend current knowledge of the pharmacokinetics of tramadol and M1 following oral administration of three doses of tramadol to horses. A total of nine healthy adult horses received a single oral administration of 3, 6, and 9 mg/kg of tramadol via nasogastric tube. Blood samples were collected...
Poth MKM, McKemie DS, Traynham M, Kass PH, Knych HK.The metabolism and pharmacokinetics of intravenous (i.v.) morphine in the horse have been described; however, administration of therapeutic doses has also been associated with neuroexcitation and adverse gastrointestinal effects. In this study, we hypothesized that oral administration would lead to comparable concentrations of morphine and its presumed active metabolite, morphine 6-glucuronide (M6G) without the adverse effects associated with i.v. administration. Eight horses were administered a single i.v. dose of 0.2 mg/kg morphine and oral doses of 0.2, 0.6, and 0.8 mg/kg of morphine in a...
Di Salvo A, Busechian S, Zappulla F, Marchesi MC, Pieramati C, Orvieto S, Boveri M, Predieri PG, Rueca F, Della Rocca G.A new formulation of omeprazole in gastro-resistant granules was tested with regard to its pharmacokinetics and tolerability. Twenty-four horses were randomly divided into three groups (8 horses/group) and treated, according a parallel study design, as follows: Group A untreated (control group), Group B received 4 mg/kg of omeprazole, and Group C received 12 mg/kg of omeprazole, both of which were treated orally once a day for 90 days. Blood samples, taken from Group B subjects during the 1st and the 29th day of treatment at pre-established time points, were used to determine the concentrat...
Tsujimura K, Yamada M, Nagata S, Yamanaka T, Nemoto M, Kondo T, Kurosawa M, Matsumura T.We investigated the pharmacokinetics of penciclovir after oral administration of its prodrug famciclovir to horses. Following an oral dose of famciclovir at 20 mg/kg, maximum plasma concentrations of penciclovir occurred between 0.75 and 1.5 hr (mean 0.94 + or - 0.38 hr) after dosing and were in the range 2.22 to 3.56 microg/ml (mean 2.87 + or - 0.61 microg/ml). The concentrations of penciclovir declined in a biphasic manner after the peak concentration was attained. The mean half-life of the rapid elimination phase was 1.73 + or - 0.34 hr whereas that of the slow elimination phase was 34.34 +...
Rivas LJ, Hinchcliff KW, Kohn CW, Sams RA, Chew DJ.To describe changes in blood constituents of horses after oral and i.v. administration of sodium bicarbonate (NaHCO3), and to determine whether the changes are dose dependent. Methods: 6 adult Standardbred mares. Methods: 3 oral doses (1,500, 1,000, and 250 mg/kg of body weight) or 1 intravenous dose (250 mg/kg, 5% solution) of NaHCO3 in 3 L of water, or water (3 L orally), were given to the mares; then changes in blood constituents were measured. Access to food and water was denied during the experiment. Blood samples were collected immediately before treatment and at hourly intervals for 12 ...
Hodgson D, Howe S, Jeffcott L, Reid S, Mellor D, Higgins A.Oral administration of altrenogest for oestrus suppression in competition horses is believed to be widespread in some equestrian disciplines, and can be administered continuously for several months during a competition season. To examine whether altrenogest has any anabolic or other potential performance enhancing properties that may give a horse an unfair advantage, we examined the effect of oral altrenogest (0.044 mg/kg), given daily for a period of eight weeks, on social hierarchy, activity budget, body-mass and body condition score of 12 sedentary mares. We concluded that prolonged oral ad...
Corado CR, McKemie DS, Knych HK.Dextromethorphan is an N-methyl-D-aspartate (NMDA) non-competitive antagonist commonly used in human medicine as an antitussive. Dextromethorphan is metabolized in humans by cytochrome P450 2D6 into dextrorphan, which is reported to be more potent than the parent compound. The goal of this study is to describe the metabolism of and determine the pharmacokinetics of dextromethorphan and its major metabolites following oral administration to horses. A total of 23 horses received a single oral dose of 2 mg/kg. Blood samples were collected at time 0 and at various times up to 96 h post drug ad...
